1. Field of the Invention
The present invention is directed to the art of paper making and relates more particularly to the formation of bales of pulp laps, to the processing of such bales, and to a baling strap material.
2. Prior Art
The science of paper making and particularly the manufacture of paper from a furnish of wood fibers is an old and well developed art.
In general, a tree is debarked and reduced to pulp fibers which are cast into a slurry from which laps or sheets are formed. The sheets or laps of felted pulp are formed generally in a location near the logging operation, into bales of desired sized (e.g. 32.times.32.times.17 inches) which may range up to 600 pounds each The laps which may be dry or may incorporate a high moisture content e.g. 10% or more, are pressed to form the bales, which are then encircled with two or more wraps of wire, typically 1/8" galvanized wire. Where a high moisture content is present the freshly formed bales exhibit very high surface moisture content which may include standing water with resultant rust staining of surface laps.
The bales, which may thereafter be air or oven dried, are then shipped to the paper processing plant which, in the normal course, may be many miles from the baling side. The bales may be stored over protracted periods between shipping and use.
Upon arrival at the processing plant it is necessary to clip and remove the baling wire, generally at a location remote form the processing machinery, separation being necessitated in part by the fact that if any portion of the wire is inadvertently introduced into the succeeding processing step (pulping, beating and refining apparatus), the processing apparatus will be damaged, resulting in downtime, a wastage liquors and furnish, and possible repair of the complex beater mechanism which generally comprises rotating knives immersed in a slurry and moving in close proximity to stationary bars in the bath.
The operation of removing the baling wire is labor intensive and is widely recognized to constitute a highly hazardous procedure since the bale is in a somewhat compressed condition with the result that the snipped wires tend to spring violently away from the bale. In addition, the wires must be carefully removed to prevent contamination of the furnish and must be disposed of at in-ground waste disposal sites to conform to relevant regulations
The cost of applying baling wire is estimated to amount to $0.50 per bale and by reason of the problems enumerated above, removal of the wire costs about $1.00 per bale. It is estimated that over 300,000 miles of baling wire material are used annually in the paper industry and that the costs of baling and wire removal approximate $50,000,000.00 per annum.
In addition to the cost inhering in the strapping and unstrapping of the bales, great difficulties are encountered in the handling of the bales after wire removal.
As noted, to avoid contamination, the unstrapping is carried out remotely from the processing apparatus and thus the cumbersome now loose pulp laps must be moved from the de-strapping to the processing location.
Notwithstanding the difficulties inhering in the handling of pulp bales by the conventional method described, such method has, for over a century, been the conventional means for processing the bales from formation to introduction in the paper making process.
It is known to fabricate packets of materials such as toxic chemicals in bags formed of PVA film whereby solutions of the chemicals may be made without handling the chemicals directly by simply immersing the packets in a container of water.
It is similarly known in order to minimize the handling of soiled linen to encompass the linen in non-sticky bags made of PVA.
Representative prior art references pertaining to PVA and its uses include the following:
U.S. Pat. No. 2,948,697 Robertson Aug. 9, 1960 PA0 U.S. Pat. No. 3,316,190 Suzumura et al Apr. 25, 1967 PA0 U.S. Pat. No. 3,374,195 Bianco et al Mar. 19, 1968 PA0 U.S. Pat. No. 3,425,972 Nobile et al Feb. 4, 1969 PA0 U.S. Pat. No. 4,119,604 Wysong Oct. 10, 1978 PA0 U.S. Pat. No. 4,155,971 Wysong May 22, 1979 PA0 U.S. Pat. No. 4,156,047 Wysong May 22, 1979 PA0 U.S. Pat. No. 4,206,101 Wysong June 3, 1980 PA0 U.S. Pat. No. 4,215,169 Wysong July 29, 1980 PA0 U.S. Pat. No. 4,267,145 Wysong May 12, 1981